Valves are widely used to provide precision flow and/or pressure control of fluids. Diaphragm valves are preferred in many applications due to the valve member being directed into and out of contact with a diaphragm, which likewise directs a valve seat into and out of engagement with the diaphragm to effect the desired fluid flow/pressure control. Other attributes diaphragm valves have are low internal volume, high sealing integrity, compact size and fast actuation/operation.
After being subjected to operational use, especially involving caustic or abrasive fluids and/or particulates or condensates, valve components, notably the valve seats, become worn or damaged so that the valve can no longer function properly. One solution is to replace the entire valve, which requires disconnecting the old valve from the connections of the using application or system, and then re-establishing those system connections. In addition to the cost of the replacement valve, care must be taken to ensure the system connections to the replacement valve do not leak.
In an attempt to address this problem, replacement valve seats have been developed. For example, U.S. Pat. No. 4,715,578 to Seltzer discloses a valve seat member composed of a synthetic resin that is threadedly engaged with the valve body, including an O-ring disposed between the valve seat member and the valve body. However, for reasons including the difference in thermal coefficients of expansion/contraction between the non-metallic valve seat member and the metallic valve body, the valve seat member is susceptible to working loose from the valve body.
Another valve construction is U.S. Pat. No. 6,854,713 to Lin et al., that discloses a valve body having a cylindrical opening formed in a flow channel for receiving a cylindrical non-metal valve base. The opening includes a groove formed in the valve body. Once the cylindrical non-metal valve base has been inserted into the cylindrical opening in the valve body, a tapered ring is directed into the inside diameter of the cylindrical non-metal valve base. Flanges extending outwardly from the ring further compress the valve base between the ring and the valve body, with the groove formed in the valve body opening sized to receive a portion of the valve base, due to expansion of the valve base. However, while being configured to address valve base expansion, U.S. Pat. No. 6,854,713 is not directed to a replaceable valve base. Moreover, the process of press-fitting the tightly fitting ring inside the valve base will necessarily deform the surface of the valve base contacting the diaphragm, which will compromise the quality of the seal between the valve base and the diaphragm. Finally, due to a portion of the valve base flowing into the groove in the opening securing the valve base within the valve body as it is deformed, it is unlikely that the valve base can be removed without damaging the valve body, which would necessitate replacement of the entire valve.
What is needed is an improved valve construction that permits replacement of the valve seat without damaging the valve body, which replacement can be accomplished with a manual hand tool.